1 // SPDX-License-Identifier: GPL-2.0-only
2 /* IEEE754 floating point arithmetic
3  * single precision
4  */
5 /*
6  * MIPS floating point support
7  * Copyright (C) 1994-2000 Algorithmics Ltd.
8  */
9 
10 #include "ieee754sp.h"
11 #include "ieee754dp.h"
12 
ieee754sp_nan_fdp(int xs,u64 xm)13 static inline union ieee754sp ieee754sp_nan_fdp(int xs, u64 xm)
14 {
15 	return buildsp(xs, SP_EMAX + 1 + SP_EBIAS,
16 		       xm >> (DP_FBITS - SP_FBITS));
17 }
18 
ieee754sp_fdp(union ieee754dp x)19 union ieee754sp ieee754sp_fdp(union ieee754dp x)
20 {
21 	union ieee754sp y;
22 	u32 rm;
23 
24 	COMPXDP;
25 	COMPYSP;
26 
27 	EXPLODEXDP;
28 
29 	ieee754_clearcx();
30 
31 	FLUSHXDP;
32 
33 	switch (xc) {
34 	case IEEE754_CLASS_SNAN:
35 		x = ieee754dp_nanxcpt(x);
36 		EXPLODEXDP;
37 		fallthrough;
38 	case IEEE754_CLASS_QNAN:
39 		y = ieee754sp_nan_fdp(xs, xm);
40 		if (!ieee754_csr.nan2008) {
41 			EXPLODEYSP;
42 			if (!ieee754_class_nan(yc))
43 				y = ieee754sp_indef();
44 		}
45 		return y;
46 
47 	case IEEE754_CLASS_INF:
48 		return ieee754sp_inf(xs);
49 
50 	case IEEE754_CLASS_ZERO:
51 		return ieee754sp_zero(xs);
52 
53 	case IEEE754_CLASS_DNORM:
54 		/* can't possibly be sp representable */
55 		ieee754_setcx(IEEE754_UNDERFLOW);
56 		ieee754_setcx(IEEE754_INEXACT);
57 		if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
58 				(ieee754_csr.rm == FPU_CSR_RD && xs))
59 			return ieee754sp_mind(xs);
60 		return ieee754sp_zero(xs);
61 
62 	case IEEE754_CLASS_NORM:
63 		break;
64 	}
65 
66 	/*
67 	 * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
68 	 */
69 	rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
70 	     ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
71 
72 	return ieee754sp_format(xs, xe, rm);
73 }
74